The present invention relates to a method for stabilizing an aliphatic higher aldehyde compound or, more particularly, to a method for stabilizing an aliphatic higher aldehyde compound during prolonged storage by remarkably reducing the formation of oxidation products of the aldehyde such as carboxylic acids and trimers of the aldehyde.
As is well known, aliphatic higher aldehyde compounds are usually unstable when prolongedly stored under atmospheric conditions. The reactions mainly responsible to the instability of the aldehyde compounds are, for example, (1) the autoxidation of the aldehyde to form a corresponding carboxylic acid according to the reaction equation EQU R--CHO+O.fwdarw.R--CO--OH, (I)
in which the symbol R denotes an aliphatic hydrocarbon group, and (2) the formation of a trimer according to the reaction equation ##STR1## in which R has the same meaning as defined above.
It is conventionally practiced to add an antioxidant to an aliphatic higher aldehyde compound with an object to increase the stability thereof in storage. This method of adding an antioxidant is, however, not quite effective to reduce the rate of the carboxylic acid formation since the reaction of the above given equation (I) proceeds autocatalytically by the carboxylic acid per se or is accelerated by ultraviolet light. The method of the antioxidant addition is much less effective when the reaction of the trimer formation is concerned.
The above described problem of the instability of aliphatic higher aldehyde compounds is particularly important in the newly developed method of pest or noxious insect control by use of a sex pheromone compound, which sometimes belongs to a class of aliphatic higher aldehyde compounds such as Z-11-hexadecenal, Z-9-tetradecenal and the like, since the method of pest control with a sex pheromone is usually performed by keeping a dispenser filled with the sex pheromone compound in the open field from which the sex pheromone is sustainedly released or emitted into the air to attract the insects a particular sex. When the aldehyde compound as the sex pheromone is oxidized under the influence of ultraviolet or converted to the trimer, the activity of the sex pheromone is naturally lost correspondingly.
Despite the above described demand in the modern pest-control technology, no effective method is known in the prior art for the stabilization of aliphatic higher aldehyde compounds.